1. Field of the Invention
The present invention relates to a substrate processing method and a substrate processing apparatus for processing a substrate with a chemical solution, and a semiconductor device manufacturing method using the same.
2. Description of the Related Art
A wet process is extensively used for a substrate processing technique in a process of manufacturing a semiconductor device or a liquid crystal display. In particular, regarding a developing process to be carried out after a photosensitive resin is photosensitized, a puddle technique has been actively studied.
In a conventional puddle technique, a chemical solution is supplied onto a substrate to be processed (target substrate) while the substrate is rotated. The chemical solution is supplied by a chemical solution supply part laid out above the substrate. However, it is very difficult for the chemical solution supply part to make uniform a dispensing pressure of the chemical solution or a chemical supply quantity per unit area at a central part and at a peripheral part of the substrate. Therefore, it has been very difficult to obtain uniform developing precision in the plane of the substrate. A problem associated with such processing precision exists similarly in a substrate processing method other than the developing process.
As developing advances, a dissolved product or a developing solution with a low concentration is generated as a byproduct of such advancement. In general, it is believed that a dissolved product or a developing solution with a low concentration inhibits dissolution of a photosensitive thin film. The dissolved product or the like is generated according to the pattern density in the substrate, and thus, is generated with a certain distribution on the substrate. Then, the dissolved product or the like is subject to a force such as a centrifugal force caused by substrate rotation, and moves on the substrate with non-uniformity. For such a reason as well, in the conventional puddle technique, it has been impossible to obtain uniform processing precision in the plane.
There is proposed a substrate processing method using a suction nozzle in order to generate the flow of a chemical solution in the course of developing. For example, in Jpn. Pat. Appln. KOKAI Publication No. 2002-252167 by the present inventors, there is proposed a nozzle comprising a chemical solution dispensing port and a chemical solution suction port and a substrate processing method using the nozzle.
The above substrate processing method is directed to a method for processing a substrate in the case where a developing solution is used as a chemical solution; namely, while dispensing the developing solution from a developing solution dispensing port, sucking the developing solution from a developing solution suction port, and then, processing the substrate while scanning the nozzle in proximity to the substrate. The above substrate processing method is one method of making a nozzle proximal to a substrate, and increasing the flow rate of a chemical on the substrate, thereby achieving replacement of the chemical between patterns, and then, reducing a pattern dimensional difference caused by a pattern density.
In a state in which the nozzle and the substrate are thus very proximal to each other, bubbles or the like exist between the nozzle and the substrate. Such bubbles cause the impairment of the uniformity of the flow of the chemical on the substrate. Specifically, the flow rate or the like of the chemical becomes different depending on an upstream side and a downstream side with respect to a position at which the bubbles exist. Therefore, there has been a demand for providing a substrate processing method and a substrate processing apparatus capable of preventing the non-uniformity of the flow of the chemical caused by the bubbles.
In addition, a wet process is used for a substrate processing technique in the steps of manufacturing a semiconductor device or a liquid crystal display. In particular, regarding the developing and etching processes after a photosensitive resin has been photosensitized, a paddle method or a spray method are actively discussed. In these methods, in general, the developing solution or etching solution has been supplied and processed on the substrate, and then, the substrate is rotated while pure water is supplied during rinse processing, thereby removing a by-product caused at the time of developing (resist residue) or metallic or organic particles and the like which may exist on the substrate. However, the by-product or particles and the like are not completely reduced, thus causing the impaired yield of photomasks or wafers.
As developing or etching advances, a dissolved product or a resist residue is produced as a by-product thereof. The product and residue float in the solution existing on the substrate, and it is believed that there is a high probability that the dissolved product, resist residue and the like exist on the vicinity of the liquid solution surface. In the latest investigation, it is found that, when the liquid on the substrate becomes thin, and then, disappears, the dissolved product, resist residue and the like existing on the liquid solution surface or in the liquid solution adhere to the substrate surface, causing a defect.
In Jpn. Pat. Appln. KOKAI Publication No. 2002-252167 described previously, there is proposed a nozzle which comprises a chemical solution dispensing port and a chemical solution sucking port and a substrate processing method using the nozzle. The document describes a case of using a developing solution as a chemical solution and relates to a method of sucking the developing solution from a developing solution sucking port while dispensing the developing solution from a developing solution dispensing port, and then, processing the substrate while carrying out scanning with the nozzle being proximal to the substrate. In more detail, by making the nozzle proximal to the substrate, the replacement of the chemical solution between patterns is achieved by increasing the flow rate of the chemical, and one method for reducing the pattern dimensional difference caused by a pattern density is provided.
A sucking part exists at the above reported nozzle. The sucking section carries out processing while sucking and removing particles such as the dissolved product or resist reside contained in the liquid solution existing on the substrate. Thus, there is an advantage that these particles can be almost removed from the top of the substrate. However, the monitoring of particles is not carried out, thus making it possible to deny a possibility that a dissolved product or a floating object such as a resist residue exists on a liquid surface.
Therefore, there is a growing demand for a technique for guaranteeing that the particles hardly exist in the liquid before drying the substrate surface. That is, there has been a demand for achieving a substrate processing method and a substrate processing apparatus capable of restricting the particles from adhering to the substrate surface after drying the substrate surface and improving the yielding.